README.adoc: refer from "NUT and Ecosystem" to "Acknowledgements for …

…NUT CI and Ops" table with vendor logos [networkupstools#2192]

Signed-off-by: Jim Klimov <jimklimov+nut@gmail.com>

README.adoc

@@ -213,6 +213,8 @@ outages, please consider sponsoring or at least "starring" it on GitHub at
 https://github.com/networkupstools/nut/ - these stars are among metrics
 which potential sponsors consider to help FOSS projects. Keeping the lights
 shining in such a large non-regression build matrix is a big undertaking!
+See <<acknowledgements-ci-ops,acknowledgements for organizations who help
+with NUT CI and other daily operations>> for an overview of the shared effort.
 
 As a FOSS project, for over a quarter of a century we welcome contributions
 of both core code (drivers and other features), build recipes and other
@@ -745,6 +747,8 @@ Acknowledgements / Contributions
 The many people who have participated in creating and improving NUT are
 listed in the user manual {xref}Acknowledgements{x-s}[acknowledgements appendix].
 
+[[acknowledgements-ci-ops]]
+
 We would like to highlight some organizations which provide continuous
 support to the NUT project (and many other FOSS projects) on technological
 and organizational sides, such as helping keep the donations transparent,